GENERAL INFORMATION About Anaesthetists Local Anaesthetics Regional Anaesthetics Inhalation Anaesthetics Sedation Blood transfusion Intensive care

PRE-OPERATIVE Fasting Medication Test

INTRA-OPERATIVE Monitoring

POST-OPERATIVE Nausea Pain

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Modern anaesthetics are administered by intravenous (IV) injection, inhalation, or both. Most of the time we give an IV agent such as propofol to send you to sleep, and keep you asleep (maintenance of anaesthesia) with an inhalational agent such as isoflurane, but a continuous IV infusion of propofol is becoming a popular technique as well. A "cocktail" of different drugs is often used, to minimise side effects and wake up time at the end. On the right is a narcotic for pain relief, below is the stuff that actually sends you off to sleep. Below right is a muscle relaxant, which relaxes your muscles to allow insertion of a breathing tube, and also to facilitate surgical access

All drugs have some unwanted, or "side-effects". Cardiac and respiratory depression are seen with almost every anaesthetic, which may make it more hazardous for people with some diseases. The commonest troublesome side effects are nausea and vomiting, so we often use a prophylactic anti-emetic agent. Narcotics like morphine and pethidine may cause nausea as well, related to the dose and individual sensitivity. We can usually treat this satisfactorily.

A general anaesthetic will make you totally unaware for the whole procedure. Most of the time you will have a general, depending on which procedure, your anaesthetist and surgeon, your pre-existing medical condition and your own preference too. General anaesthetics are generally intravenous for induction = going off to sleep. and usually inhalational for maintenance of anaesthesia. We often add a muscle relaxant drug to allow intubation of the trachea and control of the "airway", and to make the surgery easier with reduced muscle tone. A strong pain-killer like morphine is often added, and anti-nausea drugs too, with perhaps an anti-inflammatory agent.

Mostly we use a mixture of drugs, like a cocktail. By using smaller doses we can minimise the risks and possible side effects, whilst making sure you are properly asleep - and wake up within a reasonable time afterwards.

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Modern general anaesthetic drugs have improved over the years, so they have less side effects and wear off more quickly. Therefore you can usually expect to be more awake earlier, with less of a "hangover".

The most common intravenous (IV) agent is called propofol, which in most developed countries has replaced the barbiturate pentothal. It is usually given into the IV cannula (plastic tube in the vein) which has been inserted already. If that is all we gave, you would wake up in 5 to 10 minutes, so we need something to keep you asleep - for "maintenance". This is most commmonly an inhalational anesthetic agent, but we can use a continuous IV infusion of propofol instead. There are pros and cons for each tecchnique, which your anaesthetist will consider. For most situations it makes no real difference which you have. Likewise, you can go to sleep just breathing the anaesthetic gases combined with oxygen - e.g. sevoflurane, from a vaporizer like that on the left.

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Anaesthetists (or anesthesiologists in the USA) are highly specialized medical doctors, who have had extensive postgraduate training of 5-6 years learning anesthesia, following 6 years in medical school.

Anaesthetists look after you during surgery or painful diagnostic procedures, when your physiology is severely compromised, or for pain management. This includes optimising your condition before embarking on an operation, and during and after as well.

Anaesthetists started the first intensive care units, and in some hospitals still manage the unit. This will vary, generally these days a larger hospital would have its own full-time intesivists, although anaesthetis may still be involved. We have similar skills - resuscitation, airway management, restoration and maintenance of optimum physiological state, and pharmacological expertise. Sedation and pain control are also required in intensive care.

As medical doctors we have some knowledge of all areas of medicine, from paediatrics and obstetrics, to neurology and cardiology. We have to make a relatively quick assessment of your physical fitness before anaesthetising you, hence the questionaire we ask you to fill out. You may get the feeling these questions are being asked over and over, by the admitting nurse, by the anaesthetist, and the operation theatre staff. This is to make absolutely sure of all your details, we cannot ask you again once you are asleep! We may request a specialist referral if we are concerned about some aspect of your health, most commonly from a cardiologist.

We also manage acute pain, that is arising from some new insult or cause. For instance pain associated with a broken bone or other trauma, after surgery, or during labour and childbirth - most commonly with an epidural. You might have an epidural running after surgery too, or have a "PCA" (patient controlled analgesia) device to control your pain post-operatively. We also run pain clinics for the management of chronic pain (long term pain), employing medications and local anaesthetic blocks for example, or sometimes non-pharmacological techniques may help.

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Local anaesthetic drugs act locally on the nerve fibres. They block the electrical transmission by depolarising the membrane, changing from a negative to positive charge.
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You might have local anaesthetic at the dentist, or to have a mole removed. Some bigger operations can also be done with this, usually combined with some sedation.

A breast lump removal or a hernia repair might be done this way, but the degree of sedation may be significant, sometimes almost the same as having a general anaesthetic. Either way, these drugs can affect you for some time afterwards, so we say you MUST NOT DRIVE for 24 hours after receiving sedation or a GA.

Cocaine was first used to produce topical anaesthesia of the cornea, the surface of the eye. Procaine came later (novacaine), but now we use better and safer drugs with less side effects. Lignocaine (lidocaine in USA) was the first of these, developed by Swedish drug company Astra (now Astra-Zenaca). They developed a much longer acting alernative called bupivacaine (Marcaine) , but it was still potentially dangerous in large doses. The latest drug is ropivicaine (Naropin), which is a safer alternative now becoming widely used around the world.

Local anaesthetic is used generously during surgery these days, because it provides the best post-operative pain relief. Amazingly, for decades it was rarely used if you were "going to be asleep anyway"! It has mainly been anaesthetists' influence driving this acceptance by surgeons. There is also ample evidence that complications are reduced by combining local and general anaesthesia. The "stress" of surgery is minimised, with less immune system suppression, and fewer heart attacks or blood clots for example. Blood loss is also usually less, so transfusion is less likely. The whole experience is more pleasant if you get adequate local anaesthetic. Not only during the few hours it is working, but also for days or weeks later the pain levels appear to be reduced. Tell your surgeon to use lots of local!

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This is anesthesia in one region of your body. This might be just your arm - an "arm block ", or your whole lower body - a spinal, or epidural anaesthetic.

Some operations are particulary suitable for regional techniques. A spinal may be ideal for a prostate operation, or an "eye block" for a cataract extraction.
With an axial block (spinal or epidural) the first fibres to be blocked are the sympathetic, or autonomic fibres which control blood pressure and other automatic functions. The sensory ones are next - pain, temperature and position - but pressure sensation may be maintained. You might be aware of pulling or pressure, but it should not hurt! Motor block is the last to happen, stopping you from moving your arm or legs.

We commonly add a regional to a general, such as an epidural for major lower limb orthopaedic procedures, or for major abdominal/bowel surgery. This may be run as a continuous infusion afterwards, sometimes for several days. However it does not always work perfectly, and some narcotic or similar drug may be required too. There are also risks and complications associated with regional anaesthesia, which your anaesthetist may discuss - they are not suitable for everyone.

SPINAL ANAESTHETIC: above, a drop of clear CSF (cerebro-spinal fluid) hangs from the hub of the needle.

During the surgery there should be no pain , but possibly pressure sensation. If it DOES hurt then tell us, and more local, sedation, or conversion to full GA is possible, but rarely required :)

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Today we still use descendents of ether, most often isoflurane, sevoflurane, or desflurane. Nitrous oxide ("laughing gas") is still used by most anaesthetists, combined with oxygen . All these anaestheticss are admistered in precisely controlled and monitored concentrations, via the anesthesia machine (below). An inhalational anaesthetic is in liquid form at room temperature, but is vapourised into the breathing system, from an accurately calibrated, temperature controlled vapouriser.

We use inhalational inductions commonly for children, and adults sometimes too (induction is going to sleep. or inducing anesthesia). Sometimes the slower induction of anaesthesia (compared to IV) is associated with an "excitement" phase, where you may hyperventilate and move around, before settling into a satisfactory plane of anesthesia. Do not be alarmed if your child does this, if you have been allowed to accompany her or him into the operating room! Some anesthesiologists/hospitals allow parents into the O.R., others may not.

The anesthetic concentration in your lungs and body is constantly monitored, This makes sure you are getting enough to stay asleep, but not too much - which can cause unwanted effects on blood pressure and cardiac function. The newer agents are more quickly taken up and eliminated from your body, which helps us wake you up more quickly at the end, especially after a long operation.

This fast uptake means inhalational induction may be a more acceptable alternative to intravenous induction, generally using sevoflurane. Most people report being asleep within 4 - 6 breaths. Mouth breathing will reduce the flow thorugh your nose, and hence lessen the smell of the vapour. If you have a needle phobia or have poor veins, this may be good option, ask your anaesthetist if she or he doesn't suggest it. Sometimes this may not be appropriate, for example if you are quite overwight, or have been a "difficult intubation" previously.

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Sedation means reducing your level of consciousness to some degree. This reduces the anxiety that most people experience in an unfamiliar, possibly painful situation. This makes you sleepy and very relaxed, sometimes to the extent where your breating is depressed. You will have extra oxygen wia small plastic tubes in the nose, or a face-mask. We still use the same monitoring as for a general or major regional anaesthetic.

Like a general anaesthesia, sedation still persists for some time afterwards. So we ask you not to drive, or do anything where you might hurt yourself or others - like operate machinery or even cooking - for 24 HOURS.

Sedation is often used with reigionals, or for smaller procedures, where the surgeon injects local anaesthetic directly around the operation site. Usually we make you the most sleepy during this, so most of the time you will not remember that - the most painful part! You may become more awake as the operation proceeds, but it should not hurt. If it does, you will be able to have more sedation, and /or more local anaesthetic as well. If there is a problem with controlling pain for you, we would send you right off to sleep, but this is hardly ever necessary.

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Depending on the type and duration of our surgery, you will require fluid replacemnet, given intravenously via a catheter inserted into a vein. You will need more if you are dehydrated before we start, but the regular fasting pre-operatively does not usually cause a significant deficit. Serious dehydration from a bowel obstruction with vomiting, diarrhoea, or bleeding, will usually mean a delay until we get you topped up again, as the outcome is better if you are in better shape at the outset. In cases of massive ongoing blood loss such as ruptured aortic aneurysm, or severe trauma, we just carry on as the best treatment is surgery to stop the bleeding!

These days we try to avoid blood transfusion unless "absolutely necessary". But if your blood count gets dangerously low (severe anaemia), your organ function will become compromised - you may have a heart attack, or a stroke for example. So we hold off to a much lower level than we would have before HIV/AIDS appeared in the 1980's. Hepatitis is actually a bigger risk than HIV. We take in to account your specific wishes - if you are a Jehovah's witness you may want to refuse any blood products, even if they would stop you from dying.

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It may be necessary to spend some time in the intensive care unit postoperatively - or even beforehand, if you are very sick. Most commonly this would be after more major procedures such as cardiac, liver, lung or major cancer surgery. It may be a better place to optimise your outcome, if you have a serious medical problem beforehand - e.g heart or kidney failure, stroke or sepsis. A serious but rare complication like anaphylaxis/severe allergy, or malignant hyperthermia would also warrant ICU care.

In an ICU you may still have the endotracheal tube (breathing tube) in place, between your vocal cords in the larynx. This allows gas exchange directly via your trachea, oxygen in and carbon dioxide out. You cannot talk with this in place although it is surprisingly not too uncomfortable! You would be sedated to ensure a comfortable state, although you will have to wake up at some stage when everything is stable, and the tube is withdrawn. You may have other "tubes" and catheters - a urinary catheter in the bladder for example.

The ICU staff will observe you just like the anaesthetist in the operating theatre, with similar monitoring - and often more!

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Anaesthesia is not a normal state, and all the drugs we use can have serious unwanted effects. Therefore we prefer you to be in reasonable physical condition prior to embarking on a potentially perilous journey.

A bad cold, or an untreated heart condition might be a reason to defer your surgery. Of course it depends on the urgency of the procedure - is it life- threatening e.g. a ruptured aneurysm , or elective like a hip replacement? A cancer operation would be in between, important to get on with, but a delay of a week should not matter.

Please tell us everything, it is completely confidential. All medications, drugs, pills and potions you are on, or have taken recently should be disclosed - including non-prescription - herbal or natural remedies, as these may have serious side effects and interactions too.

Therefore we ask that you complete a questionaire about your past medical history. We need to know about any previous anaesthetic problems, and if there is ANY family history of any problems.

There are some rare ones like malignant hyperthermia, which are strongly familial. If any blood relative has died under or soon after anaesthesia, we should discuss this.

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- NO FOOD OR DRINK - for HOW LONG before?

Most anaesthetists are comfortable with a time of 6 hours since eating any food, or drinking "solid" fluids like milk, yoghurt or pulpy juices. It is safe to continue drinking CLEAR fluids up to 2 hours prior to your anaesthetic. Clear fluids means water, clear liquids like apple juice. Black or green tea, and coffee are OK (not excessive amounts of anything though - just a normal intake).

Babies are OK with 3 - 5 hours since bottle feeding, and 2 - 4 hours since breast feeding (we usually take the normal interval between feeds for your baby, e.g. 3 hours, and say fast for that period). They can usually commence feeding straight after waking up. Breast feeding mothers having surgery themselves may want to express some milk, in case they are not up to feeding the baby afterwards. Only small amounts of the newer anaesthetics are excreted in the breast milk, not enough to worry about for a healthy baby :)

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Which medication should I take? Generally, take EVERYTHING EXCEPT diabetic medications, as they may cause your blood sugar to drop at a time when you have no sugar intake. Do not take diabetic tablets like metformin or glipizide the night before sugery if you are scheduled in the morning. If you take insulin it may be best to have none and see where your sugar level is on arrival - we may use an infusion of insulin and sugar peri-operatively, depending on the procedure and the severity of your diabetes.

Other drugs that you definitely should take are anti-epileptics, steroid drugs like prednisone, anti-asthmatic drugs and inhalers, and anti-reflux or antacid drugs. Pain relieving drugs can be taken right up to surgery and should be used if you need them.

Please TAKE ALL cardiovascular medications or drugs on the day of surgery - blood pressure pills (anti-hypertensives), anti-angina, heart rhythm drugs etc. Diuretics or water pills, and cholesterol drugs too, though they are not so important. If you wear a patch for angina, leave it on.

Blood thinners like warfarin or coumadin should be discussed with your surgeon, as they may cause excessive bleeding, though stopping them suddenly may not be sensible either. Instead, we may use a short acting agent like heparin to regulate your clotting peri-operatively. Aspirin is a blood thinner, and your surgeon and anaesthetist should be aware if you taking it (most commonly as a heart disease/stroke preventitive measure). If you have actually had a heart attack or stroke, it may be better to continue with the aspirin.
Anti-depressants, thyroid drugs, and almost anything else except the diabetic ones should be taken as usual, including any sleeping pill you might be on if you have insomnia. Your anaesthetist will see you before your surgery, and discuss the management including any drugs you are prescribed.

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We may ask for some special investigations - blood tests for anaemia, kidney and liver function, a chest X-ray, ECG (heart tracing) , echocardiogram or other tests. If you are young, fit and healthy and having a minor procedure, you probably won't need any tests at all. If you are elderly, and/or having a major procedure, you will probably have at least some blood tests and an ECG. We may ask for another specialist's opinion, most commonly a cardiologist, a chest physician, a haematologist (clots, bleeding tendencies etc) or an endocrinologist (diabetes, thyroid etc).
You may be asked to attend a "pre-assessment" clinic, where you will discuss your heealth and the proposed anesthesia/surgery, and any potential problems anticipated.

We don't expect you to work out for weeks to attain a high fitness level! But we would like to know about any illnesses, conditions or diseases you have, or have had. Heart and lung conditions are most worrying, but also liver or kidney problems, diabetes, neurological diseases, muscular dystrophies or endocrine disorders are all important. A history of blood clots (DVT deep vein thrombosis or pulmonary embolus) gives you a higher risk for more clots, so we will take special precations. If you smoke, try to cut down or stop - ideally 6 weeks before. If this causes undue distress, try and cut down a bit and tell us if you develop bronchitis or a cold meantime.

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With general anaesthesia you will be totally unconscious during the whole procedure. We keep you asleep with either inhaled anaesthetic vapour, or injected intravenous drugs. You may receive both of these, e.g. an IV narcotic like morphine or fentanyl, combined with a gaseous agent like sevoflurane or desflurane. We usually use several drugs with different actions - pain relief = narcotic, unconsciousness = sevoflurane, or sometimes IV with propofol via an infusion pump.

As well as managing ventillation and gas exchange, we adjust your blood pressure, replace fluids or blood lost (blood transfusion only if absolutely necessary), maintain body temperautre, and watch for pressure areas or other potential hazards.

The main reason is improved monitoring of vital signs, and continuous gas analysis - particularly the carbon dioxide concentration with each breath, and the oxygen level in the blood, via a probe clipped onto your finger. These two monitors help detect virtually all serious problems before they become dangerous. Adverse events or outcomes were much more common in the past - see RISK page.

Your anaesthetist will stay in the procedure room the whole time you are anaesthetised, to check everything is running smoothly, and maintain your body functions in a normal state. Also to keep you fully asleep of course, or comfortably sedated perhaps, with a regional or local anesthetic.

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Monitoring comes form the Latin word moneo - I WARN!

Not just watching the screen, but anticipating problems before they occur. The alarms are more "intelligent" now, and will alert us to potentially dangerous changes in time to correct it - e.g. turn down the anesthetic, turn up the oxygen or speed up the I.V., perhaps give other drugs to increase or decrease the blood pressure.

Everyone should have the blood oxygen saturation measured with a probe that clips on a finger or thumb (right, and 2nd tracing above in yellow = 97%). The carbon dioxide level in the expired breath is also monitored (bottom blue trace). The inspored oxygen concentration (red = 36), and the anesthetic concentration (purple = 1.3) should also be measured. Blood pressure, pulse rate and heart tracing (ECG, on top), and temperature are usually monitored too.

For more major surgery - heart, liver or brain surgery perhaps, or if you are medically compromised, we may prefer to use more "invasive" monitoring - e.g. an arterial line placed inside an artery, usually the radial at the wrist. This gives us a beat to beat display of the blood pressure, so a trend is noticed more quickly than with the usual blood pressure cuff reading every 5 minutes. Or we may like to measure the "central venous" pressure (CVP) with a catheter inserted usually into the internal jugular vein in your neck. This has potential complications like a pneumothorax (a punctured lung) for instance, though it is rare and usually of no consequence. We would weigh up the pros and cons, and discuss it with you before we use this invasive monitoring.

A catheter or tube in your bladder tells us your urine output for major/ longer cases as well. This may be a bit uncomfortable afterwards, most commonly a feeling that you "need to pee", but just try and relax and let it go as if you were on the toilet, you wont make a mess as it is all being done for you!

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AFTER YOUR ANAESTHESIA and OPERATION - RECOVERY/PACU

When the procedure has finished, we wake you up by turning off the anaesthetic drugs. They are generally faster to wear off than they once were, so you should awaken more quickly, with less "hangover" effects. The PACU (post anesthesia care unit) is where this happens, monitored by trained nurses who know how to deal with any problems. You usually get some extra oxygen from a facemask or little tubes in the nose. Pain will be controlled, if you are suffering significant discomfort, just tell the nurse - see PAIN page.

Problems in the recovery room (PACU) include breathing difficulties - e.g. still a bit "paralysed" from the muscle relaxant drugs, or airway obstruction if still very sleepy. Heart rhythm or blood plessure changes may occur, as they can during anaesthesia - or at any time. You will be fully monitored for these eventualities, until you are well awake and stable, and quite comfortable with minimal pain or nausea.

Temperature control is a major problem during anaesthesia, especially longer ones. The normal homeostatic mechanisms are disabled, so you get cold quickly especially if left uncovered. We can usually limit this with special warming blankets, fluid warmers, and respiratory humidifiers.

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Nausea/vomiting is still one of the most common side effects/problems associated with anaesthesia. The use of propofol in particular has reduced it significantly, being much less nauseating than the previously used barbiturate drugs such as pentothal. So if you had nausea after your last procedure 10 or more years ago, it is likely that should be lessened or abolished next time. Nausea may be caused by central nervous system effects, or from the gut - a bowel obstruction, infection or blood in the stomach for instance. Nausea can also result from ear and balance disorders. We usually give an anti-emetic drug, sometimes even 2 or 3 different ones as a prophylaxis against PONV (post-operative nausea and vomiting). We may also use an antacid to reduce the stomach acid (raise the pH), especially if you have a history of heartburn/acid reflux.

There are several types of drug to choose from, and they act in at least 3 different ways so one of them should work. Similarly, you may need repeat doses of these in PACU (or " recovery"), or in the ward later. We can try different ones if they are not working. Unfortunately, all the strongest pain-killers (narcotics like morphine etc) have nausea as a side effect, and it is dose related. So if you require alot of these, you may well suffer some nausea, though we can still usually relieve it for you. Use of milder pain-killers first, alone or in combination, may reduce the narcotic requirement and hence the nausea . Some people may have to choose between a bit of pain and no nausea, or vice versa - the use of a PCA (pain control pump) makes this an easier choice for you. Please tell the nurses if you are nauseated or in pain, or anything else concerns you.

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Many hospitals now have an acute "pain team", who help to manage this important part of your care.

Everyone has a different perception of pain, as it is subjective in nature. What one person finds excruciating may be quite OK for someone else, depending on past experience, genetics, cultural factors, expectations and anxiety levels. The best way is to let you, the patient decide how much pain relief you need, which is best done using a PCA (= patient controlled analgesia) device. This is usually a syringe pump, with a button you push which administers a dose of (usually) morphine or another narcotic drug. If you use it when you feel the pain is bad enough, it should work very well. Some people may need quite alot, others may not even use it at all after the same kind of surgery. If used responsibly it is very safe - and you will not get addicted to anything in just a few days. An epidural can also be used continously (by infusion) for some time afterwards. When it is turned off, it may become sudddenly quite painful, so consider some pre-emptive analgesia here too, ask the doctor about it.

That's it if you managed to read this far! Follow the links below, if you want more info.

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